Safely accesses deep properties of objects.
// npm install drilldown
// bower install drilldown
var dd = require('drilldown');Strict version locking is recommended during release 0.0.x
Ever run into this?
var foo;
foo.bar;
// TypeError: Cannot read property 'bar' of undefinedYou can now check deeply nested properties cleanly!
var foo = {abc: {def: {ghi: 'jkl'}}};
dd(foo)('abc')('def')('ghi').val is 'jkl'
dd(foo)('abc')('zzz')('yyy').val is undefined
// You don't need to use this ugly idiom anymore!
(((foo || {}).abc || {}).def || {}).ghi // noCheck if a deep property exists:
dd(foo)('abc').existsWorks with arrays too:
var foo = {abc: [ {bar: 'def'},{bar: 'ghi'} ]};
dd(foo)('abc')(0)('bar').val is 'def'Safely call functions:
var foo = {abc: {addOne: function(x) { return x + 1; }}};
dd(foo)('abc')('addOne').invoke(5); returns 6
dd(foo)('zzz')('aaa').invoke(5); returns undefinedUpdate values if the original value exists:
var foo = {abc: {def: {ghi: 'jkl'}}};
var newValue = {ping: 'pong'};
dd(foo)('abc')('def').update(newValue);
// - foo is now {abc: {def: {ping: 'pong'}}}
// - {ping: 'pong'} is returned
dd(foo)('abc')('zzz').update(5);
// - foo is unchanged
// - undefined is returnedSet values even if the path drilled to does not exist:
var foo = {abc: {}};
dd(foo)('abc')('def')('ghi').set('jkl');
// - foo is now {abc: {def: {ghi: 'jkl}}}To prevent confusion, only own properties are drilled into.
Available dd properties:
- val - the value
- exists - true if val is defined
- update function(value) - sets the value if the value exists
- set function(value) - sets the value at any path
- invoke - the value if the value is a function, or else a dummy function
Alternatives:
- lodash or underscore:
_.get(foo, 'abc.def.ghi') - nevernull:
nn(foo)('abc.def')('ghi').val - vanilla es5:
(((foo || {}).abc || {}).def || {}).ghi
Drilldown works with dots and brackets in property names, which may be useful for drilling with user input.